Like many others have already said, I'm not really concerned with the government. I'm sure they have all the info they feel they need on me, and can easily gather anything else they want.
It's others I'm concerned about. A few years back I had a question for Dennis on TFL (by the way, is Dennis still around?), so I e-mailed him. In his reply he asked if I was the same so-and-so that lived in such-and-such city, was born on such-and-such date, had posted to such-and-such websites, had this, did that, etc. All this info he had gathered through a basic web search. Though he never said it outright, I believe he was trying to give me the hint that I should exercise a bit of prudency when online. Because really, I had never given a second thought to anything like that. I was fairly new to the internet, and had no idea that what I would put out there basically stayed there, and was accessible via simple searches, as I verified myself shortly thereafter by doing my own searches. I was really taken aback, and in hindsight I'm grateful to Dennis for showing me just how much about myself I was making freely available to the entire world. My online habits changed almost immediately. Add to that all the reading I've done on identity theft since then, and the many examples of criminal misuse of basic information gathered online and elsewhere, and you get the picture. Being cautious with what I put online is a free and simple step to help minimize the risk to my safety and well-being, similar to locking the doors on my car and house, wearing my sealbelt, tucking my clothes in when working around machinery and power tools, etc. Why open myself or my family up to unnecessary risk?